Vascular function curve and systemic blood pressure

[Mcat35]

Can someone explain this statement to me. Increased right atrial or systemic pressure and or decreased blood volume decreases venous return to the heart (decreased preload), and vice versa.

I understand the decreased blood volum part but why does an increase in right atrial or systemic pressure also do this?

Thanks

Does it have to do with increasing systemic pressure which backs up all the way to the Left ventricle which affects the afterload on the left ventricle resulting in less blood volume in the systemic circulation?

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[pirsquared]

The way I think about is, "how much blood is getting back to the heart?".

So decreased blood volume makes sense.

Now let's consider increased RA pressure. If the RA pressure is increased, the pressure gradient is decreased, and less blood returns to the RA.

For increased systemic pressure, if your arteries constrict, less blood can be put into them (decreased compliance), so less blood can return to the heart.

 

[SpecterGT260]

The blood backs up. It's basically as simple as that. If you had to write an essay about it the poster above me gave the vest answer.

When in doubt, take things to the extreme. What happens if you increase RA pressure to above that of the venous return? Theoretically the flow would reverse. Any increase over normal will reduce the amount that can flow in during diastole.

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[Mcat35]

makes sense thanks to you both